Hydrocarbon Filling Ages and Evolution ofthe Silurian Asphalt Sandstones in Tarim Basin

Key words: 
• Tarim basin /
• Silurian /
• asphalt sandstone /
• filling age evolution /
• hydrocarbon accumulation

Abstract: From the Silurian period, there have been three times of hydrocarbon generation and expulsion for the lower Paleozoic source rocks in Tarim basin, and the hydrocarbon generation ages of the lower Paleozoic and the trap formation ages of the Silurian together controlled the filling ages and evolution of the Silurian asphalt sandstones. After being formed in early of the Silurian, the Silurian asphalt sandstones underwent several sedimentary and tectonic events and three times of hydrocarbon filling and mixing, and these made the original distribution and occurrence of asphalt in the Silurian paleo-oil reservoirs complicated. The three times of hydrocarbon filling to the Silurian asphalt sandstones are as follows: the first time of filling took place in the late Caledonian, the second from the late Hercynian to Indosinian, and the third from the Yanshanian to Himalayan. Therefore, the mixture of asphalt, heavy oil, and normal oil and gas shows that the Silurian asphalt sandstones are the result of the three times of hydrocarbon filling.